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Advanced Programming in the UNIX Environment
Week 3: Union Mounts and Whiteout Files
One of the file types we've encountered are those of type S_IFWHT, so called "whiteout" files. But what the hell is that?? Let's illustrate! We describe the concept of union mounts and see what happens when a file in the upper layer is removed while the same file still exists in the lower layer: a whiteout file is created to cover up the lower file.
Advanced Programming in the UNIX Environment
Week 4: The Unix Filesystem
In this video lecture, we begin a closer look at the Unix Filesystem (UFS). We visualize how the filesystem structures the disk and organizes files and directories. We illustrate how directory entries are created and moved around.
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Advanced Programming in the UNIX Environment
Week 4: The Unix Filesystem
In this video lecture, we begin a closer look at the Unix Filesystem (UFS). We visualize how the filesystem structures the disk and organizes files and directories. We illustrate how directory entries are created and moved around.
Advanced Programming in the UNIX Environment
Week 4: Links
In this video lecture, we'll take a look at the system calls used to create, remove, and rename both hard- and symbolic links. We'll compare expected output against trivial implementations of the ln(1) and mv(1) commands.
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Advanced Programming in the UNIX Environment
Week 4: Links
In this video lecture, we'll take a look at the system calls used to create, remove, and rename both hard- and symbolic links. We'll compare expected output against trivial implementations of the ln(1) and mv(1) commands.
Advanced Programming in the UNIX Environment
Week 4: Directories
In this video lecture, we take a look at how directories are created and removed, as well as how to move around the filesystem hierarchy. We also learn why the 'cd' command must be a shell builtin in order to work.
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Advanced Programming in the UNIX Environment
Week 4: Directories
In this video lecture, we take a look at how directories are created and removed, as well as how to move around the filesystem hierarchy. We also learn why the 'cd' command must be a shell builtin in order to work.
Advanced Programming in the UNIX Environment
Week 4: Directory Size
In this video lecture, we dive deep into the structure of the directory on a traditional Unix File System and see how its size is independent of the file sizes of its entries, but dependent on the filename lengths. We'll also use hexdump(1) to cheat a bit and look at the directory structure on disk.
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Advanced Programming in the UNIX Environment
Week 4: Directory Size
In this video lecture, we dive deep into the structure of the directory on a traditional Unix File System and see how its size is independent of the file sizes of its entries, but dependent on the filename lengths. We'll also use hexdump(1) to cheat a bit and look at the directory structure on disk.
Advanced Programming in the UNIX Environment
Week 4: /etc/passwd
In this short video, we try to answer the awkward question "Mommy, where do UIDs come from?". We look at the /etc/passwd user database and identify the various fields before we look at how things can get weird.
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Advanced Programming in the UNIX Environment
Week 4: /etc/passwd
In this short video, we try to answer the awkward question "Mommy, where do UIDs come from?". We look at the /etc/passwd user database and identify the various fields before we look at how things can get weird.
Advanced Programming in the UNIX Environment
Week 4: getpwuid(2) and /etc/groups
In this video lecture, we look at the library functions used to look up account information. We learn about how primary and supplementary groups are handled as well as how the hashed passwords are stored outside of the world readable /etc/passwd file.
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Advanced Programming in the UNIX Environment
Week 4: getpwuid(2) and /etc/groups
In this video lecture, we look at the library functions used to look up account information. We learn about how primary and supplementary groups are handled as well as how the hashed passwords are stored outside of the world readable /etc/passwd file.
Advanced Programming in the UNIX Environment
Week 4: atime, mtime, ctime
In this video lecture, we start looking a little bit closer into what our systems think of "time", something that experts most accurately describe as a big ball of wibbly, wobbly, timey, wimey... stuff. In short, analyze how the atime, mtime, and ctimes of a file connect.
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Advanced Programming in the UNIX Environment
Week 4: atime, mtime, ctime
In this video lecture, we start looking a little bit closer into what our systems think of "time", something that experts most accurately describe as a big ball of wibbly, wobbly, timey, wimey... stuff. In short, analyze how the atime, mtime, and ctimes of a file connect.
Advanced Programming in the UNIX Environment
Week 4: time(3) is an illusion
Having revisited the atime, mtime, and time in our last video segment, we now have to come to terms with time(3) itself. We'll discuss managing the data structures and handling arbitrary concepts such as leap seconds, timezones, and (ugh) Daylight Savings Time. It gets silly real quick.
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Advanced Programming in the UNIX Environment
Week 4: time(3) is an illusion
Having revisited the atime, mtime, and time in our last video segment, we now have to come to terms with time(3) itself. We'll discuss managing the data structures and handling arbitrary concepts such as leap seconds, timezones, and (ugh) Daylight Savings Time. It gets silly real quick.
Related to our discussion of time(3), here's a deeper dive into the Unix epoch, its origins, and how the Y2K38 issue actually affects different unix systems well before the heat-death of the universe.
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Related to our discussion of time(3), here's a deeper dive into the Unix epoch, its origins, and how the Y2K38 issue actually affects different unix systems well before the heat-death of the universe.
Advanced Programming in the Unix Environment
Week 5: The Unix Development Environment
This week, we cover the concept of the Unix userland as an Integrated Development Environment. This introduction outlines the different tools we will cover in subsequent videos, including the editor, the compiler chain, make(1), the debugger, and code revision and management tools. No vibe coding here.
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Advanced Programming in the Unix Environment
Week 5: The Unix Development Environment
This week, we cover the concept of the Unix userland as an Integrated Development Environment. This introduction outlines the different tools we will cover in subsequent videos, including the editor, the compiler chain, make(1), the debugger, and code revision and management tools. No vibe coding here.
Advanced Programming in the Unix Environment
Week 5: The Editor
In this video lecture, we look at the required feature for a full-fledged programmer's editor and illustrate some of the core functionality by example of vim(1). This includes basic motion commands, setting and moving to markers, using folds, and the use of the ':make' and quick fix lists to address compiler errors efficiently.
(Don't worry, we'll talk about ed(1) later.)
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Advanced Programming in the Unix Environment
Week 5: The Editor
In this video lecture, we look at the required feature for a full-fledged programmer's editor and illustrate some of the core functionality by example of vim(1). This includes basic motion commands, setting and moving to markers, using folds, and the use of the ':make' and quick fix lists to address compiler errors efficiently.
(Don't worry, we'll talk about ed(1) later.)
Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part I
In this video lecture, we begin our discussion of compilers as part of the Unix programming environment. We provide a high-level overview of how compilers process input source code and turn it into an executable.
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Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part I
In this video lecture, we begin our discussion of compilers as part of the Unix programming environment. We provide a high-level overview of how compilers process input source code and turn it into an executable.
Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part II
In this video lecture, we look at the preprocessing stage of the compiler and observe how it invokes the cpp(1) command to include header files or replace macro definitions in place.
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Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part II
In this video lecture, we look at the preprocessing stage of the compiler and observe how it invokes the cpp(1) command to include header files or replace macro definitions in place.
Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part III
In this next-to-last part on the compiler chain, we look at the compilation proper and the optimization and assembly of the intermediate code into an object file. (We will revisit some of this when we take a closer look at shared libraries in week 11.)
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Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part III
In this next-to-last part on the compiler chain, we look at the compilation proper and the optimization and assembly of the intermediate code into an object file. (We will revisit some of this when we take a closer look at shared libraries in week 11.)
Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part IV
In this video lecture, we conclude our discussion of the compiler chain, analyzing the last step in the process: linking the object files into the executable. We identify aspects of the C Runtime libraries as well as the standard C library that we need to include and cover a few of the most important flags to ld(1).
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Advanced Programming in the Unix Environment
Week 5: The Compiler Chain, Part IV
In this video lecture, we conclude our discussion of the compiler chain, analyzing the last step in the process: linking the object files into the executable. We identify aspects of the C Runtime libraries as well as the standard C library that we need to include and cover a few of the most important flags to ld(1).
Advanced Programming in the Unix Environment
Week 5: make(1)
Moving on from the compiler, we now look at how the make(1) utility can be used to help us selectively build our code project.
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Advanced Programming in the Unix Environment
Week 5: make(1)
Moving on from the compiler, we now look at how the make(1) utility can be used to help us selectively build our code project.
Advanced Programming in the Unix Environment
Week 5: Debugging your code
Next in our discussion of the Unix _development_ environment, we start a short series on the use of a debugger by example of gdb(1). First, we illustrate just why exactly we might want to use a separate tool instead of sprinkling "printf" statements all over our code...
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Advanced Programming in the Unix Environment
Week 5: Debugging your code
Next in our discussion of the Unix _development_ environment, we start a short series on the use of a debugger by example of gdb(1). First, we illustrate just why exactly we might want to use a separate tool instead of sprinkling "printf" statements all over our code...
Advanced Programming in the Unix Environment
Week 5: Using gdb(1)
Alright, let's look at gdb(1)! We begin by using it to troubleshoot our failing programs and immediately identify the location of our program where it segfaults. We also see how to inspect variables and call functions from within the debugger.
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Advanced Programming in the Unix Environment
Week 5: Using gdb(1)
Alright, let's look at gdb(1)! We begin by using it to troubleshoot our failing programs and immediately identify the location of our program where it segfaults. We also see how to inspect variables and call functions from within the debugger.
Advanced Programming in the Unix Environment
Week 5: Using gdb(1), part II
In this video lecture, we continue to explore the capabilities of the debugger. We show how you can set a breakpoint to pause the program and how to step through the program while watching our code.
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Advanced Programming in the Unix Environment
Week 5: Using gdb(1), part II
In this video lecture, we continue to explore the capabilities of the debugger. We show how you can set a breakpoint to pause the program and how to step through the program while watching our code.
Advanced Programming in the Unix Environment
Week 5: Using gdb(1), part III
In this video lecture, we'll use our newly learned debugging skills to analyze and fix yet another flawed program. In the process, we learn to debug code from multiple source files and find out how to change the value of variables while the program is running.
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Gli ultimi otto messaggi ricevuti dalla Federazione
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@jonny "my French lover, le Chat GPT". Jesus Christ. She's coming in hot with the red flags, and the book I want is how to never meet her.
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Roma: il “villaggio sportivo” dell’esercito al quarticciolo. “e’ propaganda militare mascherata da iniziativa sociale”
@anarchia
Martedì 21 ottobre, al Quarticciolo, quartiere della periferia est di Roma, verrà allestito un villaggio sportivo organizzato dall’Esercito Italiano presso la parrocchia Ascensione NSGC. L’iniziativa
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the ghoulish hollowness of soul to even formulate the idea "i want to be the kind of person who has written a book about how to date me, but i don't want to write it, but i do want to sell it for $4.99"
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RE: https://neuromatch.social/@jonny/115409736697961808
where is Hunter S. Thompson when you need a "The chatGPT girlboss dinner is decadent and depraved"
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The Lambda Papers: When LISP Got Turned Into a Microprocessor
The physical layout of the SCHEME-78 LISP-based microprocessor by Steele and Sussman. (Source: ACM, Vol 23, Issue 11, 1980)
During the AI research boom of the 1970s, the LISP language – from LISt Processor – saw a major surge in use and development, including many dialects being developed. One of these dialects was Scheme, developed by [Guy L. Steele] and [Gerald Jay Sussman], who wrote a number of articles that were published by the Massachusetts Institute of Technology (MIT) AI Lab as part of the AI Memos. This subset, called the Lambda Papers, cover the ideas from both men about lambda calculus, its application with LISP and ultimately the 1980 paper on the design of a LISP-based microprocessor.Scheme is notable here because it influenced the development of what would be standardized in 1994 as Common Lisp, which is what can be called ‘modern Lisp’. The idea of creating dedicated LISP machines was not a new one, driven by the processing requirements of AI systems. The mismatch between the S-expressions of LISP and the typical way that assembly uses the CPUs of the era led to the development of CPUs with dedicated hardware support for LISP.
The design described by [Steele] and [Sussman] in their 1980 paper, as featured in the Communications of the ACM, features an instruction set architecture (ISA) that matches the LISP language more closely. As described, it is effectively a hardware-based LISP interpreter, implemented in a VLSI chip, called the SCHEME-78. By moving as much as possible into hardware, obviously performance is much improved. This is somewhat like how today’s AI boom is based around dedicated vector processors that excel at inference, unlike generic CPUs.
During the 1980s LISP machines began to integrate more and more hardware features, with the Symbolics and LMI systems featuring heavily. Later these systems also began to be marketed towards non-AI uses like 3D modelling and computer graphics. As however funding for AI research dried up and commodity hardware began to outpace specialized processors, so too did these systems vanish.
Top image: Symbolics 3620 and LMI Lambda Lisp machines (Credit: Jason Riedy)
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@reiver provocative!
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As a biologist, I have determined that shorebirds can be divided into 6 categories:
- Short bill long legs fren
- Fancy billed big bois
- Short billed round bois
- Short kings w big bills
- Long legged supermodels
- Silly-lookin' babies
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When I die, I want my kids to get a dog and name him Dad.
